554 research outputs found
Neutron-Unbound Excited States of 23N
Neutron unbound states in 23N were populated via proton knockout from an 83.4 MeV/nucleon 24O beam on a liquid deuterium target. The two-body decay energy displays two peaks at E1âŒ100keV and E2âŒ1MeV with respect to the neutron separation energy. The data are consistent with shell model calculations predicting resonances at excitation energies of âŒ3.6MeV and âŒ4.5MeV. The selectivity of the reaction implies that these states correspond to the first and second 3/2â states. The energy of the first state is about 1.3 MeV lower than the first excited 2+ in 24O. This decrease is largely due to coupling with the Ïpâ13/2 hole along with a small reduction of the N=16 shell gap in 23N
Novel technique for constraining r-process (n,) reaction rates
A novel technique has been developed, which will open exciting new
opportunities for studying the very neutron-rich nuclei involved in the
r-process. As a proof-of-principle, the -spectra from the -decay
of Ga have been measured with the SuN detector at the National
Superconducting Cyclotron Laboratory. The nuclear level density and
-ray strength function are extracted and used as input to
Hauser-Feshbach calculations. The present technique is shown to strongly
constrain the Ge()Ge cross section and reaction rate.Comment: 5 pages, 3 figure
Charged-current neutrino-208Pb reactions
We present theoretical results on the non flux-averaged
and
reaction cross sections, obtained within the charge-exchange
Random-Phase-Approximation. A detailed knowledge of these cross sections is
important in different contexts. In particular, it is necessary to assess the
possibility of using lead as a detector in future experiments on supernova
neutrinos, such as OMNIS and LAND, and eventually detect neutrino oscillation
signals by exploiting the spectroscopic properties of . We discuss
the present status on the theoretical predictions of the reaction cross
sections.Comment: 5 pages, latex, 3 figures. added discussion on present status,
Submitted to Phys.Rev.
Two-Neutron Sequential Decay of O
A two-neutron unbound excited state of O was populated through a
(d,d') reaction at 83.4 MeV/nucleon. A state at (stat) (sys) keV with a width of MeV was observed above the
two-neutron separation energy placing it at 7.65 0.2 MeV with respect to
the ground state. Three-body correlations for the decay of O
O + show clear evidence for a sequential decay
through an intermediate state in O. Neither a di-neutron nor phase-space
model for the three-body breakup were able to describe these correlations
Spectroscopy of 13B via the 13C(t,3He) reaction at 115 AMeV
Gamow-Teller and dipole transitions to final states in 13B were studied via
the 13C(t,3He) reaction at Et = 115 AMeV. Besides the strong Gamow-Teller
transition to the 13B ground state, a weaker Gamow-Teller transition to a state
at 3.6 MeV was found. This state was assigned a spin-parity of 3/2- by
comparison with shell-model calculations using the WBP and WBT interactions
which were modified to allow for mixing between nhw and (n+2)hw configurations.
This assignment agrees with a recent result from a lifetime measurement of
excited states in 13B. The shell-model calculations also explained the
relatively large spectroscopic strength measured for a low-lying 1/2+ state at
4.83 MeV in 13B. The cross sections for dipole transitions up to Ex(13B)= 20
MeV excited via the 13C(t,3He) reaction were also compared with the shell-model
calculations. The theoretical cross sections exceeded the data by a factor of
about 1.8, which might indicate that the dipole excitations are "quenched".
Uncertainties in the reaction calculations complicate that interpretation.Comment: 11 pages, 6 figure
Assisted reproductive technology in Europe, 2007: results generated from European registers by ESHRE
Peer reviewedPublisher PD
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